Flow cytometry has become an essential technique in modern biomedical research, and is important for the research programs of many Cold Spring Harbor investigators. Recent improvements in technology have vastly improved the capabilities of flow cytometry analysis and cell sorting. In this application, we request funding for the purchase of a Cytometrics MoFlo Ultra High-Speed flow cytometer, which we are requesting to replace an outdated flow cytometer operated through the Flow Cytometry Shared Resource in the Cold Spring Harbor Laboratory Cancer Center. The MoFlo instrument is "state-of-the art," and has a number of features that will improve the capabilities of flow cytometry at CSHL. Importantly, the Moflo is capable of very high sorting speeds (nearly 100 times our current capacity), is extremely stable, and offers a level of flexibility not possible in comparable machines. As a result, the sorting capacity of our facility will greatly increase, and it will be better able to meet the current and future needs of CSHL investigators. Eight CSHL investigators will be major users of the MoFlo flow cytometer. Because the machine will be incorporated to a facility supported by the CSHL Cancer Center, it can be readily integrated into an existing management, operation, and maintenance structure. The improvements in flow cytometry research that will result from upgrading our current equipment will facilitate the continued success of each user's research program.